A hydraulic excavator which is s typical example of a construction machine is constituted by a self-propelled lower traveling structure, an upper revolving structure rotatably mounted on the lower traveling structure, and a working mechanism provided on a front side of the upper revolving structure, capable of moving upward/downward. Moreover, the upper revolving structure has a revolving frame forming a support structural body, and a prime mover, a hydraulic pump, a heat exchanger, a fuel tank and the like are mounted on this revolving frame.
Here, in order to check an oil amount (liquid level) of a fuel stored in the fuel tank, provision of a level gauge in the fuel tank is known (see Patent Document 1). In this case, an exterior cover covering the fuel tank is provided on the hydraulic excavator. An opening portion (inspecting window) for visually checking the level gauge from outside the exterior cover is formed at a portion corresponding to the level gauge of the fuel tank in the exterior cover. As a result, a worker can check the oil amount in the fuel tank by visually checking the level gauge through the opening portion from outside the exterior cover.